This invention relates to automotive vehicle seat systems and, more particularly, to lightweight, high strength, economical seat track assemblies usable in such systems.
Automotive seating systems usually comprise a pair of seat track assemblies each including a lower track member mounted to the floor of the vehicle and an upper track member carrying a seat and slideably engaged with the lower track member for adjusting the position of the seat in the vehicle. The upper track members are coupled so as to move simultaneously one with the other. The system is also associated with seat or safety belt means designed to restrain a seat occupant in the event of a vehicle impact.
Automotive seating systems are considered part of the vehicle occupant's protection or safety systems. Accordingly, various requirements are imposed on such seating systems. They must have high strength and structural integrity so that the seat remains anchored to the vehicle in the event of a crash, i.e., the seat tracks should not separate from the vehicle, from each other or from the seat. Test requirements embodied in U.S. Federal Vehicle Safety Standards 208 and 210 require that the seating systems withstand loads of 1500 to 3000 pounds without failure. The outboard (adjacent the door) lower part of the seating system and each seat belt should withstand a load of 1500 pounds and the inboard (adjacent the centerline) lower part should withstand 3000 pounds. In addition, increased emphasis on fuel economy necessitates vehicle weight reduction. This, of course, makes it highly desirable to reduce the weight of the seating system, but mere weight reduction can adversely impact the strength the seating system.
Cost containment is still another requirement imposed on automotive vehicle seating systems and prior art attempts to meet all three requirements, high-strength--lightweight--low cost, have not been satisfactory. Some attempts have been made to substitute aluminum for steel in the design of the seat track assemblies. These designs required steel reinforcements to provide the required structural strength and these reinforcements add weight and cost to the systems.
Another desirable advantage for automotive seating systems is the integration of the seat or safety belt means so that the track assemblies, seat and seat belts are a self-contained unit. If the seat belts were integrated with the seat and track assemblies, adjustment of the seat by the occupant would not require readjustment of the seat belts. It would also facilitate the installation of the seat belts in convertible vehicles where no pillars are readily available. Usually the seat belt means are anchored to the vehicle body pillar and floor to reduce the loads imposed on the seat track assemblies during a crash. Attempts to integrate all of the seat belts with the seat and seat track assemblies aggravate the strength and weight considerations noted above.